1. Field of the Invention
The present invention relates to a toroidal type continuously variable transmission (referred to as T-CVT hereinbelow) which has an input disk, an output disk and power rollers sandwiched and frictionally engaged between the input and output disks and transmits rotational power between the input and output disks via the power rollers at a transmission ratio variable according to the inclination of the power rollers relative to the input and output disks.
2. Description of the Prior Art
In the T-CVT of the above-mentioned basic construction which itself is well known in the art, it is a general construction that the input disk is supported by an input shaft and the output shaft is journaled on the input shaft to be rotatable therearound. Such a general construction that the input and output disks are both commonly supported by the input shaft provides a T-CVT at a smaller size and a lower weight for the same power transmission capacity, by a smaller number of construction members, and therefore at a lower manufacturing cost, as compared with a T-CVT having input and output shafts supporting the input and output disks separately.
However, since the input disk and output disks of the T-CVT rotate in opposite directions relative to one another, when the output disk is journaled on the input shaft, the bearing means which supports the output disk on the input shaft is subjected to a very high rotation speed which is an addition of the rotation speed of the input disk and that of the output disk, and therefore the bearing means often suffers an early wearing. Further, on the other hand, since the input disk is generally rotatably supported on the input shaft via a bearing means so that the input disk is axially biased relative to the input shaft by a torque cam means which converts a part of the torque into an axial force based upon an angular shifting of the input disk relative to the input shaft, such a bearing is subjected to a very small rotation and generally suffers uneven wearing of the bearing surface.